Long-range versus short-range interactions and the configurational energies of Ba(B, B ')O-3 and Pb(B, B ')O-3 perovskites

摘要

Total energy calculations were performed for three perovskite related ordered supercells in several stoichiometries of A(B, B')O-3; where A is Pb2+ or Ba2+; B is Mg2+, Zn2+, SC3+ or In3+; and B' is Nb5+,Ta5+ or W6+. A striking difference between the Pb and Ba(B, B')O-3 systems is that the differences in total energies for Pb-systems span ranges that are consistently smaller than those of the Ba systems. This indicates a reduction in the energetic barriers to disordering in the Pb-systems, which is consistent with experimental observations of consistently higher transition temperatures in the Ba-systems. This trend is explained as a consequence of enhanced Pb-O bonding to underbonded oxygens in B2+-O-B2+ and B3+-O-B3+ environments. [References: 43]